"But isn't marijuana addictive?". National Organization for the Reform of Marijuana Laws. Retrieved 2.19.08 - Substantial research exists regarding marijuana and addiction. While the scientific community has yet to achieve full consensus on this matter, the majority of epidemiological and animal data demonstrate that the reinforcing properties of marijuana in humans is low in comparison to other drugs of abuse, including alcohol and nicotine. According to the U.S. Institute of Medicine (IOM), fewer than one in 10 marijuana smokers become regular users of the drug, and most voluntary cease their use after 34 years of age. By comparison, 15 percent of alcohol consumers and 32 percent of tobacco smokers exhibit symptoms of drug dependence.

According to the IOM, observable cannabis withdrawal symptoms are rare and have only been identified under unique patient settings. These remain limited to adolescents in treatment facilities for substance abuse problems, and in a research setting where subjects were given marijuana or THC daily. Compared with the profound physical syndrome of alcohol or heroin withdrawal, marijuana-related withdrawal symptoms are mild and subtle. Symptoms may include restlessness, irritability, mild agitation and sleep disruption. However, for the overwhelming majority of marijuana smokers, these symptoms are not severe enough to re-initiate their use of cannabis."

In 1972, President Richard Nixon commissioned the National Commission on Marihuana and Drug Abuse to produce an in-depth report on marijuana. The report, entitled "Marihuana: A Signal of Misunderstanding," reviewed existing marijuana studies and concluded that marijuana does not cause physicial addiction.[2]